Method of and apparatus for dispensing liquefied petroleum gas



Feb. 24,1948. L. J.-w|-|m-: v2,436,731

METHOD OF AND APPARATUS FOR DISPENSING LIQUEFIED PETROLEUM GAS Filed March a, 1944 2 Sheets-Sheet 1 PRESSURE REDUCING REGULRTOR v I 5E3 ans ssnvm: PIPE I j J /8 1 uousnso PETROLEUM cnssronna's w TANK 1948. L. J. WHITE 2,436,781

METHOD OF AND APPARATUS FOR DISPENSING LIQUEFIED PETROLEUM GAS Filed March 8, 1944 2 Sheets-Sheet 2 PRESSIIJRE REDUCING REGULHTORS ,2? i 635 SERV CE PIPE LIQUEFEU PETROLEUM GHS STORAGE TANK I I I I I I I I I I I I I I, [0

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alleyway Patented Feb. 24, 1948 UNiTED STATES PATENT OFFICE.

METHOD OF AND APPARATUS FOR 'msrnnsma LIQUEFIED rurnommu GAS Loyd J. White, San 'Antonio, Tex assignor .to Southern Steel Company, San Antonio, Tex., a corporation of Texas Application March 8, 1944, Serial No. 525,582

This invention relates to a method of and apd which utilizes heat derived indirectly from the contents of the storage tank transmitted by a heating medium to the cold spot or coldest portion of a pressure reducing valve to prevent contained moisture from freezing and causing the valve to stick and fail to function; Still another aim is to provide improved heat exchanging means utilizing someheat derived from the contents of the tank to transfqr heat to the cold spot of the pressure reducing valve.

Other aims and advantages of the invention will appear in the specification, when considered in connection with the accompanying drawings, wherein:

Figure 1 is a diagrammatic illustration partly in section showing a batch vaporization system embodying the invention; and

Fig. 2 is a diagrammatic illustration similar to Figure 1 showing a two-stage liquid eduction system.

Referring more particularly to the drawings, the illustrative apparatus shown in Fig. 1 is applied to a batch vaporization system, wherein liquefied petroleum gas is stored in a. pressure storage tank I0 and the vapor, generated .therein, is delivered through a conduit I I. The conduit may be in the form of a standpipe and the appurtenances employed for filling and delivering the gas at low pressure through the service pipe may be similar to those shown in my prior patents based on such systems. The high pressure gas delivered from the tank passes through a. pressure reducing valve l2 which is controlled by an ordinary regulator I 3 of the diaphragm type. Such regulators are well known in the art and require no detailed description. The pressure reducingvalve reduces the pressure of the gas to about six ounces or to the desired service pressure and it passes through a conduit l4 and a heat exchanging coil I! to the gas service pipe ii.

In accordance with this invention, the casing of the pressure reducing valve I2 is arranged in heat exchange contact with a heating medium confined in a heat exchanger II. By way of illustration, the heat exchanger is shown as being 5 Claims. (Cl. 62-1) in the form of a container which is filled with kerosene or some other liquid having a relatively low freezing point. A conduit I8 is shown as being connected to the bottom of the container I! and passes downwardly into the tank ill to a point near the bottom; thence upwardly through a heat exchanging coil l9 and return conduit to a point near the top of the container ll, the arrangement being such that the liquid heating medium will circulate through the conduit due to the-absorption of heat from the contents of the tank l0. In other words, the latent or sensible heat of the liquid in the tank Ill sets up thermosiphonie circulation of the liquid heating medium and the heating medium gives up heat to the i cold spot of the pressure reducing valve l2. Fur- 'thermore, the heating medium also exchanges its heat with the coil IS in the outlet conduit leading to the service pipe and insures complete vaporization of the gas. Any condensate which collects in the outlet conduit M will be revaporlzed by absorption of heat from the liquid heating medium. Experience has demonstrated that valves of the type usually employed in batch' vaporization systems are subject to sticking due to freezing of the moisture contained in the gas. This arrangement is designed to prevent the freezing of moisture in the valve and to eliminate the foregoing diiliculty under normal operating conditions.

7 Referring particularly to Fig. 2, the system shown therein is designed to deliver liguefied petroleum gas from the storage tank ill, due to the vapor pressure generated therein, through a liquid eduction conduit 2 I; Then, a portion .of the liquid is flashed into vapor as it passes through a first-stage pressure reducer and the residuum of the liquid is converted into vapor between the first-stage pressure reducer and a second-stage pressure reducer. Thence, the gas is delivered at service pressure through a gas service pipe.

In this instance the liquid is delivered through the first-stage pressure reducing valve 22 which is controlled by the usual diaphragm regulator 23. The liquid is partially flashed into vapor and passes through heat exchanging coils 24 to a seccud-stage pressure reducing valve 25 which is controlled by a second-stage diaphragm regulator 26. Thence, the gas passes through the service pipe 21 at the desired service pressure.

-In the example shown in Fig. 2, the pressure reducing valves of the first and second stage regulators are shown as being arranged in heat exchange contact with a liquid heating medium, such as kerosene, in the heat exchanger 28, simi- 3 lar to the heat exchanger shown in Figure 1. The bottom of the heat exchanger is shown as being inclined downwardly and a circulating pipe or ing the gas in the liquid phase from the tank due to the pressure therein through a first-stage conduit 29 is connected thereto and leads into the bottom portion of the storage tank Hi. It is shown as having a heat exchanging coil 30 and a return conduit 3i connected to the upper por- .tion of the heat exchanger 28. The arrangement is similar to that shown in Figure 1 and provides for the thermo-siphonic circulationof the liquid heating medium due to the absorption of heat from the contents of the tank and the exchange of heat with the cold spots of the two pressure reducers, as well as the delivery of heat to vaporize the residuum of liquid between the two stages in the coils 24. However, it will be understood that the residuum of liquid between the two pressure reducers may be vaporized by other mean well known in the art.

From the foregoing description, it will be seen that the method involves the transfer ofheat from the contents of the storage tank through a liquid heating medium to the cold spots of the regulator valves to prevent sticking due to freezing of the moisture in the gas or in theliquid. Furthermore, it will be understood that the apparatus shown for illustrative purposes is capable of a wide variety of modifications. It can be employed in connection with systems such as those shown in my prior Patents No. 2,176,829, No. 2,214,713 and No. 2,225,579, as well as other types of apparatus used for dispensing either butane or propane and commercial mixtures thereof. Moreover, the .method and apparatus herein disclosed are adaptable for use in either underground or above-ground systems.

Obviously, this invention is not restricted to the particular embodiments thereof herein shown and described, and is capable of a wide variety of modifications.

What is claimed is: I

1. The method of dispensing liquefied petroleum gas which is characterized by storing the gas under pressure in a storage tank, delivering the fuel as needed through a pressure reducing valve; submerging the pressure reducing valve in heat exchanging contact within a body of liquid heating medium; and using the cooling effect to assist in thermo-siphonically circulating the liquid heating medium through a conduit in heat exchanging relation with the contents of the storage tank to absorb heat therefrom, whereby the liquid heating medium prevents moisture from freezing as it passes through the pressure reducing valve and thereby prevents the valve from sticking.

2. The method of dispensing liquefied petroleum gas which is characterized by storing of the liquefied gas in a pressure storage tank; deliverpressure reducing valve; passing the vapor and liquid through a heat exchanger to a secondstage pressure reducing valve and, thence, to a gas service pipe; exposing both pressure reducing valves to heat exchange contact with a liquid heating medium; and deriving heat from the contents of the storage tank to raise the temperature of the liquid heating medium.

3. The method as set forth in claim 2 wherein the heat exchanger between the first and second stage pressure reducing valves also absorbs vaporizing heat from the liquid heating medium.

- 4. Apparatus for dispensing liquefied petroleum gas comprising, in combination, a pressure storage tank; a conduit connected to the tank to deliver fuel therefrom; a pressure reducing valve for reducing the pressure of the fuel; a heat ex- ,changer carrying a liquid heating medium submerging the casing of the pressure reducing valve; and a conduit connected to the heat exchanger and arranged in heat exchanging contact with the contents of the storage tank to cause the liquid heating medium to circulate through the heat exchanger.

5. In a liquefied petroleum gas dispensing-system of the type wherein the fuel is stored in a pressure storage tank, a liquid eduction conduit connected to the storage tank to deliver liquid therefrom; a first-stage pressure reducing valve through which the liquid passes and partially flashes into vapor; a heat exchanging coil through 'which the fuel is delivered from the first-stage 35 pressure reducing valve; a second-stage pressure reducing valve connected to the heat exchanging coil to deliver the gas at service pressure; a heat exchanger filled with a liquid heating medium arranged in heat exchange contact with both pressure reducing valves and said heat exchanging coil; and a conduit leading from the bottom portion of the heat exchanger into the bottom portion of the storage tank and back into the upper portion of the heat exchanger arranged in heat exchanging contact with the contents of the pressure storage tank to set up thermosiphonic circulation through the heat exchanger.

LOYD J. WHITE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,166,911 Little July 18, 1939 2,286,050 Baker et a1. June 9, 1942 2,393,545 Martin Jan. 22, 1946 2,400,570 Norway May 2, 1946 

